1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material having improved antistatic property and more particularly to a photographic light-sensitive material having an improved antistatic property without detrimentally influencing photographic properties.
2. Description of the Prior Art
Photographic light-sensitive materials generally comprise an electrically insulative support and one or more photographic layers. Electrostatic charges often accumulate during the production of photographic light-sensitive materials or upon use thereof generated as the light-sensitive material contacts surfaces such as a roller or guide surface or the surface of an adjacent roll of film during wind up. This accumulation of electrostatic charge can result in many problems, the most serious of which is the formation of spots or tree-like or fur-like lines (so-called static marks) upon developement of the exposed photographic film. These marks are formed by discharge of the accumulated electrostatic charge before development. Static marks seriously spoil the commercial value of photographic films and, in an extreme case, render the film useless. For example, it can readily be understood that such static marks on X-ray films for medical or industrial use could lead to an incorrect diagnosis. This phenomenon presents an extremely difficult problem because it is only observed after development. In addition, the accumulated electrostatic charge can cause secondary problems such as adhesion of dust to the film surface and non-uniform coating.
As explained above, such electrostatic charges often accumulate upon production and use of photographic light-sensitive materials. In the production steps, the electrostatic charge develops due to contact friction between photographic films and rollers or separation of the support surface from the emulsion surface during the film-winding or film-unwinding. With finished products, it develops due to separation of a base surface and an emulsion surface from each other upon winding up and changing films or contact or separation of X-ray films with or from mechanical members or fluorescent brightening paper in an automatic photographing machine.
Static marks in photographic light-sensitive materials formed by the accumulated electrostatic charge become more serious as the sensitivity of the photographic light-sensitive material increases and as the processing speed increases. Particularly, photographic light-sensitive materials have recently often been subjected to severe processing conditions to increase sensitivity, high-speed coating, high speed photographing, high speed automatic processing, etc., and hence static marks occur more readily.
The best solution to the static electricity problem is to increase the conductivity of the photographic materials, thus allowing the charge to dissipate in a short time prior to discharge of the accumulated charge.
Thus, attempts have been made to improve the conductivity of the support and various surface-coating layers of photographic light-sensitive materials using various hygroscopic materials, water-soluble inorganic salts, certain kinds of surfactants, polymers, etc. Thus, the polymers described in, for example, U.S. Pat. Nos. 2,882,157, 2,972,535, 3,062,785, 3,262,807, 3,514,291, 3,615,531, 3,753,716, 3,938,999, etc., the surfactants described in, for example, U.S. Pat. Nos. 2,982,651, 3,428,456, 3,457,076, 3,454,625, 3,552,972, 3,655,387, etc., and zinc oxide, semi-conductors, colloidal silica, etc., described in, for example, U.S. Pat. Nos. 3,062,700, 3,245,833, and 3,525,621, have been used to combat the static mark problems.
However, the properties of these materials are so specific and depend so much upon the kind of the film support and the photographic composition, that while they provide good results with some particular film supports and photographic layers, they are completely useless for preventing development of static electricity with other film supports and photographic layers and, in some cases, exert a detrimental influence on the photographic properties. In particular, it has been extremely difficult to prevent development of electrostatic charges on a hydrophilic colloidal layer and, in many cases, there results an insufficient reduction in surface resistance under low humidity or adhesion problems arise between the photographic light-sensitive materials or between a photographic light-sensitive material and other surfaces under a high temperature and a high humidity conditions.
On the other hand, some materials cannot be used to increase conductivity due to their adverse effect on the photographic properties such as sensitivity of photographic emulsions, fog, graininess, sharpness, etc., in spite of their excellent antistatic effect. For example, polyethylene oxide series compounds, generally known to have an antistatic effect, often exert a detrimental influence on photographic properties such as an increase of fog, desensitization, deterioration of graininess, etc.
In particular, it has been difficult to effectively impart an antistatic property to light-sensitive materials having photographic emulsions on both sides of the support such as X-ray sensitive materials for medical use without detrimentally influencing the photographic properties. As explained above, application of an antistatic agent to photographic light-sensitive materials is extremely complex and the use of the agent is often restricted.